Acute pancreatitis (AP) is an inflammation of the pancreas gland and the most common gastrointestinal discharge diagnosis (approximately 280,000 admissions in 2009). It has resulted in $2.6 billion, annually, in health care costs, mainly due to the more serious forms of the disease. Lack of any specific drug to treat the condition and predictors to identify patients who will develop more serious forms of the disease contribute to this. Long-term objectives of the study are to find a drug to treat this disease, improve patient outcomes, and reduce the costs of health care. Based on our experience with animals and a small, human subjects pilot study, our hypothesis and specific aims are: 1. Pentoxifylline, administered within 72 hours of diagnosis, improves the clinical outcomes and decreases the occurrence of more serious forms of AP. 2. Pentoxifylline reduces the blood levels of inflammatory markers, which correlates with improvement in clinical outcomes. This study is a novel, exploratory clinical study of the effect of a drug that has a proven role in animal studies in blocking the inflammatory response in AP. It is also a high reward study that will lead to a breakthrough in the treatment of AP and challenge the age old recommendation of supportive treatment alone. Thus it aligns extremely well with the NIH mission of R21 grants. The study will have 2 groups of 64 patients each, all with AP, randomly assigned to either the drug or a placebo, which looks like the drug, for a period of 7 days or until the time they are discharged, if hospital discharge is within 7 days of admission. The levels of markers of inflammation (CRP, IL-6, IL-8 and TNF-a) will be measured at baseline and on 5 successive days or until the time of discharge, whichever occurs earlier. Determination of group size was based on the previous pilot study to decrease any of the important adverse outcomes, providing for a dropout rate of 10% during the study. During 2012, 263 patients with AP were admitted to this institution, which possesses the needed infrastructure for successful completion of clinical drug intervention trials. In the stipulated period of 2 years by the NIH, the required number of patients for the study could be recruited.